Abstract

Image-guided radiotherapy (IGRT) provides precise positioning for the tumor target, but it may bring extra irradiation dose in the target positioning with a cone beam CT (CBCT) which has been increasingly used in IGRT. In this work, we focused on biological effects of the low-dose irradiation in IGRT, which have not been considered so far. Primary human fibroblasts cells from the lung and MRC-5 were irradiated by a CBCT. DNA double-strand breaks (γ-H2AX foci) and micronucleus frequency of the irradiated samples were analyzed. Compared to the control, the γ-H2AX foci yields of the samples irradiated to 16 mGy increased significantly, and the micronuclei rate of the samples irradiated for 3 days increased notably. The dose by imaging guidance device can be genotoxic to normal tissue cells, suggesting a potential risk of a secondary cancer. The effects, if confirmed by clinical studies, should be considered prudentially in designing IGRT treatment plans for the radiosensitive population, especially for children.

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This work was supported by the Strategic Priority Research Program of Chinese Academy of Sciences (No. XDA03040000), the National Natural Science Foundation under Grant No. 30900386, the Anhui Provincial Natural Science Foundation under Grant Nos. 090413095 and 11040606Q55, and the National Natural Science Foundation of Department of Education of Anhui Province under Grant No KJ2010B380.

Notes

Acknowledgements

The members of FDS Team have offered a large amount of help to this work. We thank Professor Lijun WU of Hefei Institutes of Physical Science, Chinese Academy of Sciences, for providing the MRC-5 cell line.